In microelectronic applications, polymers that demonstrate high temperature resistance are generally well known. Precursors of such polymers, such as polyimides and polybenzoxazoles can be made photoreactive with suitable additives. The precursors are converted to the desired polymer by known techniques such as exposure to high temperatures. The polymer precursors are used to prepare protective layers, insulating layers, and relief structures of highly heat-resistant polymers.
Conventional positive-working photosensitive polybenzoxazoles (PBO) contain an alkaline soluble PBO precursor and a diazoquinone photoactive compound as shown in U.S. Pat. No. 4,371,685. The diazoquinone compound inhibits the solubility of the PBO precursor in an aqueous base. After exposure to light, the diazoquinone compound undergoes photolysis and converts to indenecarboxylic acid, which promotes the aqueous base solubility of the PBO precursor. U.S. Pat. Nos. 6,177,225 and 6,127,086 teach the use of a PBO precursor, which contains diazoquinone moieties attached to its backbone along with a diazoquinone photoactive compound in positive-working photosensitive polybenzoxazole (PBO) compositions. Recently U.S. patent application Ser. No. 10/793337 disclosed a composition containing a polybenzoxazole precursor backbone mixed with a PBO precursor, which contained diazoquinone moieties attached to its backbone and at least one photoactive compound such as a diazoquinone compound. U.S. patent application Ser. No. 10/796587 disclosed a composition based on a PBO precursor, which contained diazoquinone moieties attached to its backbone and had the amines at the end of the polymer chain capped by various moieties and a diazoquionone photoactive compound. U.S. patent application Ser. No. 10/793341 discloses photosensitive polybenzoxazole precursor compositions that contained diazoquinone moieties attached to its backbone and contained diazoquinone compounds without active hydrogen in their structures. Such compositions provided light color films upon curing. U.S. patent application Ser. No. 10/796587 also disclosed a composition containing a PBO precursor, which contained diazoquinone moieties attached to its backbone and had the amines at the end of polymer chain capped by various moieties and had at least one photoactive compound (PAC) without active hydrogen to produce a light color film upon curing. In the art described above, the diazoquinone moiety employed in the photoactive compound was of a single type. Mixed diazoquinone compounds were not considered.
U.S. Pat. No. 4,818,658 disclosed a photoactive compound that was the reaction product of curcumin with 5-naphthoquinone diazide sulfonyl compounds and 4-naphthoquinone diazide sulfonyl compounds. U.S. Pat. No. 5,612,164 disclosed a positive photoresist comprising a trihydroxyphenylethane containing both 5-naphthoquinone diazide sulfonyl group and 4-naphthoquinone diazide sulfonyl group, and a trihydroxybenzophenone containing both 5-naphthoquinone diazide sulfonyl group and 4-naphthoquinone diazide sulfonyl group. German Patent No. DD 289,265 disclosed a photoactive compound containing both 5-naphthoquinone diazide sulfonyl group and a 4-naphthoquinone diazide sulfonyl group. U.S. Pat. No. 6,524,764 disclosed positive-type photosensitive polyimide and polybenzoxazole precursor compositions with photoactive compound containing both 5-naphthoquinone diazide sulfonyl group and 4-naphthoquinone diazide sulfonyl group. The 5-naphthoquinone diazide sulfonyl group and 4-naphthoquinone diazide sulfonyl group could be in the same molecule or in a mixture of two photoactive components.